Too many instances of Google App Engine running?

Question

I'm working on a project that has both a frontend and backend in Google App Engine, using modules. I'm getting contradicting information from my admin console, namely in my quota usage.

On one hand, when I look at the currently running instances in the "Instances" section of the "Main" section, I see only one running instance (for both front and backend, with recent requests on both)

However, when looking at the instances graph for both modules, the graph indicates that up to 4 instances have been started up (front and back). The quota usage also reflects this, as I'm eating the quota 4 times faster than usual.

The front end module is configured as threadsafe=true and automatic scaling (default). The back end module is also threadsafe and is set with basic_scaling with a max_instances: 1

For the backend specifically, there were never concurrent requests made to it. Only a few different requests within a 10 minute timeframe. Each request was completed long before the next one was called.

Am I misunderstanding something in the instance concept of GAE?

Note: I'm aware of the 15 minute penalty

Answer 1

This is probably because you have set your modules to use instance classes higher than the default of B1/F1. See the documentation on instance classes:

When you are billed for instance hours, you will not see any instance classes in your billing line items. Instead, you will see the appropriate multiple of instance hours. For example, if you use an F4 instance for one hour, you do not see "F4" listed, but you will see billing for four instance hours at the F1 rate.